1. Field of the Invention
This invention relates to a process for producing a powder of .beta.-type silicon carbide.
2. Description of the Prior Art
.beta.-Type silicon carbide, because of its transition temperature, is called a low-temperature type silicon carbide, and is available in a finer particle size and more active form than .alpha.-type silicon carbide. It is therefore, useful as a lapping powder, a material for pigments, matrix-forming materials for refractories, and a sintering material for silicon carbide sintered bodies.
According to conventional processes, for example those disclosed in British Pat. No. 1,199,953, and Japanese patent application (OPI) Nos. 75600/75 (corresponding to U.S. patent application Ser. No. 414,128, filed Nov. 8, 1973) and 37898/76, the method for preparing the starting materials is complicated, and a heating atmosphere free from oxygen is required in order to achieve high purities and high yields. Furthermore, high temperatures exceeding 1,400.degree. C and heating for long periods of time, e.g., at least about 2 hours, are required. Hence, a special apparatus, such as a high temperature variable atmosphere furnace, which is inefficient, non-productive and uneconomical, must be used when such processes are employed. Further, this apparatus is greatly limited in procedure and manufacturing techniques. Accordingly, a powder of .beta.-type silicon carbide is not readily available, and the industrial utilization of .beta.-type silicon carbide is naturally limited.